1. 31 pairs of spinal nerves Nerves consist of:
Epineurium- Dense layer of collagen fibers that surrounds a peripheral nerve.
Perineurium- Connective tissue partition that separates adjacent bundles of nerve fibers in a peripheral nerve.
Endoneurium- Delicate network of connective tissue fibers that surrounds individual nerve fibers.

2. Figure 13.8 A Peripheral Nerve

3. Spinal nerves
White ramus- Nerve bundle containing the myelinated preganglionic axons of sympathetic motor neurons en route to the sympathetic chain or to a collateral ganglion.
Ganglion/ganglia- Collection of neuron cell bodies outside of the CNS.
Gray ramus- Bundle of postganglionic sympathetic nerve fibers that are distributed to effectors in the body wall, skin, and limbs via a spinal nerve.
Dorsal ramus- Contains somatic motor and visceral motor fibers that innervate the skin and skeletal muscles of the back.
Ventral ramus- Supplies ventrolateral body surface, structures in the body wall, and the limbs.
Each pair of nerves monitors one dermatome.
Dermatome- Sensory region monitored by the dorsal rami of a single spinal segment.

4. Figure 13.9 Peripheral Distribution of Spinal Nerves
Figure 13.9a

5. Figure 13.9 Peripheral Distribution of Spinal Nerves
Figure 13.9b

6. Figure 13.10 Dermatomes Anterior (a) and posterior
(b) distributions of dermatomes
on the surface of the skin.
Figure 13.10

7. Nerve plexus Complex interwoven network of nerves Four large plexuses:
Cervical plexus- Consist of the ventral rami of spinal nerves C1-C5.
Branches innervate the muscles of the neck and extend into the thoracic cavity, where they control the diaphragmatic muscles.
Brachial plexus-Innervates the pectoral girdle and upper limb, with contributions from the ventral rami of spinal nerves C3-T1.
Lumbar plexus and Sacral plexus -Arise from the lumbar (T12-L4) and sacral (L4-S4) segments of the spinal cord, respectively, and innervate the pelvic girdle and lower limbs.

8. Figure 13.11 Peripheral Nerves and Nerve Plexus

9. Figure 13.12 The Brachial Plexus

10. Figure 13.13 The Branchial Plexus
Figure 13.13a, b

11. Figure 13.13 The Branchial Plexus
Figure 13.13c

12. Figure 13.14 The Lumbar and Sacral Plexuses
Figure 13.14a, b

13. Figure 13.14 The Lumbar and Sacral Plexuses
Figure 13.14c, d